The so-called alternate driving method has conventionally been applied to a number of active matrix type liquid crystal display devices. This method is measures against degradation phenomena such that material properties of liquid crystal are changed when the liquid crystal is driven with DC voltage for a long time and its resistance decreases, and is intended to invert the polarity of the driving voltage to apply to the liquid crystal on a frame basis. The more specific basic operation is disclosed in Non-Patent Document 1 and so on.
Basically, flicker occurs when the polarity inversion frequency of the driving voltage is one-half the frame frequency. In the alternate driving method, by averaging the polarity inversion in a screen spatially and temporally, the fundamental component of the optical response ripple is made at the frame frequency or more, thereby preventing an occurrence of flicker (visible flicker). More specifically, any one pixel and its adjacent pixels (or adjacent row of pixels or column of pixels) are made different in driving voltage polarity, and further, their polarities are inverted on a frame basis.
In this conventional technique, a polarity inversion rate of the driving voltage is high, and for this reason, the driving circuitry has a tendency to require large power consumption. In contrast thereto, Patent Document 1 filed by the same applicant as in the present invention is intended to make power savings while keeping a form of alternate driving. The addressing method according to this is a matrix addressing method for alternately driving pixels arranged in matrix, wherein: a plurality of row electrodes extending in a horizontal direction of a display screen are made to be selectively active for each horizontal scanning period of images to be displayed; a plurality of column electrodes extending in a vertical direction of the display screen are applied with respective pixel voltages that are responsive to the image and correspond to the horizontal scanning period while the pixel voltages have polarities alternating for each frame period of the images; and the pixel voltages have polarities alternating in the vertical direction spatially in a display area within the frame period, the method including: successively sequencing on a time series an application timing of the pixel voltages for one row electrode and an application timing of the pixel voltages for the other row electrode, the pixel voltages for the other row electrode being to be in the same polarities as the pixel voltages for the one row electrode; and activating the corresponding row electrode in response to each of the application timings of the pixel voltages for the one and the other row electrodes.
In Patent Document 1, such a method offers achievement of reduction in power consumption in that a polarity inversion rate of pixel voltages on the time axis is made lower while keeping a spatial inversion form of polarities of pixel voltages on a screen at the conventional alternating pattern.
[Non-Patent Document 1] Publication ‘Liquid Crystal Display Technology-Active Matrix LCD-’ MATSUMOTO, Shoichi, Nov. 14, 1997, 2nd Impression, Sangyo Tosho Kabushiki Kaisya, pages 69 to 74
[Patent Document 1 ] Japanese Patent Application Laid-Open No. 2003-114647 (particularly see Claims, FIGS. 2 and 3, and Paragraphs [0031] to [0059])